That old Mephisto, the one who watches you as you sleep and clicks ancient murmurs in your ears. Constantly plotting, stalking, and breathing on helpless infants at night, his will is to be fulfilled. Be not too hasty to call his name, for he is always listening.

Drunk Bitch: "Mephisto is a bunch of horse shit!"
Mephisto (suddenly appearing): Proceeds to slice her face into a thousand pieces.

Mephisto is short for Meph·is·toph·e·les
Pronunciation: "me-f&-'stä-f&-"lEz
Function: noun
Etymology: German
: a chief devil in the Faust legend- Me·phis·to·phe·lian /"mef-&-st&-'fEl-y&n, m&-"fis-t&-/ or Me·phis·to·phe·lean /same, or "me-f&-"stä-f&-'lE-&n/ adjective

Fallen Archangel.
Was the apprentice of Michael and was going to be lord of heaven, but lost it to Jesus because of the fall. Some say he left by himself and was not driven out.
Now he is The Duke of Hell, The Judge of the Damned, Lord of Fear and Nightmares, second only to Luciferin the hierarchy of hell